Compass compensating device.



' A. DA. McNEVlN.

COMPASS COMPENSATING DEVICE.

APPLICATION FILED JAN. II. 1911.

11. fi o Pafsentefl Jan. 15, 1918.

-r AvAILAeLe COPY ALFRED DA. MGNEVIN, 035' DETROIT, MICHIGAN.

COMPASS COMPENSATING DEVICE.

Specification of Letters Patent. Patented Jam, J15, llflljlgo Application filed January 11, 1917. Serial No. 141,733.

To all whom it may concern:

Be it known that I, ALFRED DA. McNnvIN, a citizen of the United States, residing at Detroit, in the county of Wayne and State of Michigan, have invented certain new and useful Improvements in Compass Compensating Devices, of which the following is a speci cation, reference being had therein to the accompanying drawings.

My invention relates to a new and improved compensating device for compasses, having for its object, among other things, to provi e a simple and effective mechanism that will minimize the influence of adjacent metal upon a "compass, which mechanism may be attached to a compass and be adjustable in relation thereto.

To these, and other ends, my invention consists in the compass compensating device, having certain details of construction and combinations of parts, as will be hereinafter described and more particularly pointed out in the claims.

Referring to the drawings, in which like numerals of reference designate like parts in the several figures;

Figure. 1 1s a plan view of apompass mounted within a binnacle or box with my improved devices connected therewith;

Fig. 2 is a side elevation thereof;

Fig. 3 is an enlarged sectional view of my improved device taken upon line 3-3 of Fig. 2; and

a Fig. 4 isa similar sectional view taken pon line 4-4 of Fig. 2.

In the drawings the reference numeral 1 represents the compass, which is shown herein as mounted upon trunnions 2 within a ring 3 that .is mounted upon trunnions d in the binnacle or box 5, the needle of the compass being designated by the numeral 6 and to which is attached the usual card 7.

The form, shape and style of the compass and the binnacle or boxwithin which it is contained, are not material to my invention, which may be appliedto compasses and binnacles or boxes of forms entirely difierent from that herein shown.

y improved device consists of abase 8, which is secured to the binnacle or box by screws 9 or similar means; a tube or cylinder 10 having a cap 11 threaded upon one end thereof and which is fixed to a circular head 12, which is rotatably mounted within a recess 13 in the base 8 and in the periphery of which is an annular groove 14.

Adjustable radially within the base 8 are the retaining screws 15, the points of which project into the annular groove 14, thereby providing means for locking the cylinder 10 and head 12 in any position about its axis and preventing accidental disengagement of the circular head 12 from said base 8, while at the same time permitting the same to be rotated therein.

Mounted within'the cylinder 10 is a plurality of magnets 16, in length at least equal to the needle 6, and these are held against endwise movement by a lock screw 17.

This device isattached as a unit to a compass, with the center of the'magnets 16 line with the lubberpoints of the compass, and one is preferably secured to each of three sides of the compass so as to exert their influence upon three sides thereof.

The influence of the magnets 16 upon the compass needle varies with the position they occupy in relation thereto and this is determined by the position of said magnets about the axis of the head 12. Therefore, by reason of this rotary mounting of each of thesesets of magnets 16, the influence. of the metal upon a compass can be minimized and in some casesehtirely neutralized on any adjusting point of the compass by manipulating the" magnets on either the ends or sides of the box or binnacle, even though the semi-circular deviation is greater upon *one side of the compass than upon the other sides, by varying the position of either or all of the magnets 16 about their correspond ing rotary axes.

lhe shape of the base 8 and the method of rotarily. mounting the cylinder 10 therein may be varied considerably within the spirit of my invention, and in other ways the details of my device may be modified without departing from the essential plan and scope of my invention. 1 would therefore have it understood that I do not limit myself to the exact construction herein shown and described, but claim all that falls fairly within the spirit and scope of the appended claims.

Having described my invention, what ll claim as new'and desire to secure by Letters Patent, is

1. In a device of the character described, the combination with a base member; of a tube member, the axis of which is at an angle to said box member; means for connecting said tube member with said base member, so

that it may be rotated about the axis of said base member; means for locking said tube member in any of its adj usted positions; and a magnet connected with said tube member.

2. In a device of the character described, the combination with a base member designed to be secured in a fixed .position; a tube member; one or more magnets connected with said tube member; means for holding said magnets against, movement in relation to said tube member; means for rotatably mounting said tube member on said base member about an axis transverse to said member; and means for locking said tube member against movement.

3. In a device of the character described, the combination with a base member; of a magnet; and means for rotatably connecting said magnet with said base member whereby it may move about an axis transverse to said magnet.

4. The combination with a compass; of means for minimizing the efi'ect of metal thereon, said means comprising a plurality of magnets rotatably mounted upon more than one side of said compass upon an axis transverse to said magnets.

5. In a device of the character described, the combination with a recessed base member; of a tube member having a head thereon projecting into the recess in said base member; means, connected with said base member, for holding said tube member against accidental disengagement therefrom and against movement in any of its positions; and means connected with said tube member for preventing relative movement of said magnets.

In testimony whereof I have hereunto affixed my signature.

- ALFRED DA. MCNEVIN. 

